Blue Lake

BY DOUGAL TOWNSEND (GNS)
Accessibility: MODERATE
Blue Lake with North Crater behind, J.Thomson / GNS Science
Blue Lake fills an eruption crater on northern Tongariro volcanic complex and the Tongariro Alpine Crossing track passes along the southwest rim.
Blue Lake, D.Townsend / GNS Science
The crater is formed from layers of scoria and ash, as well as agglutinated spatter sheets (blobs of lava that have stuck together after they landed from a fire fountain, forming a sheet). It has subsequently filled with rainwater, forming Blue Lake. GeoNet monitors the chemistry of the lake water occasionally to look for any signals that suggest changes in activity from magma below. A lava flow erupted at some stage from the crater and extends about 1.3km down the Mangahouhounui Valley to the east.
Edge of Blue Lake, D.Townsend / GNS Science
How big is it? The crater is about 500 m wide (the lake itself is 450 m diameter). How old is it? Some eruptions were in the last ice age, but we can't rule out activity since then. Can you find an outlet for the lake? How do you think it keeps from overflowing?
Directions/Advisory

You will pass Blue Lake when on the Tongariro track, about 1km north of Red Crater.

Be prepared for Alpine Conditions, with good footwear and sun, wind and rain protection.
All waterways including the lakes on Tongariro and his peaks Ngauruhoe and Ruapehu are sacred to local iwi, Ngāti Hikairo ki Tongariro. Kaumātua Te Ngaehe Wanikau asks visitors to the area to respect the sanctity of the maunga tapu (sacred mountains) by not touching or entering any of the waterways including the alpine lakes. Ngāti Hikairo ki Tongariro places extreme importance on their guardian role in protecting Tongariro and his peaks.

Google Directions

Click here for Google driving directions

Accessibility: MODERATE

Part of the Tongariro Alpine Crossing

Features
Volcanic Landform Geothermal
Geological Age
Last ice age through to possibly the current interglacial (Holocene)
Zealandia Evolution Sequence
Pākihi Supergoup: 5 million years ago – present
Links
The geological map and booklet for Tongariro is a fantastic resource: https://shop.gns.cri.nz/gnsgm4/